November 02, 2011

Earliest sapiens remains in Europe

They may be yellowed and worn but these ancient teeth and jaw fragment have something very revealing to say about how modern humans conquered the globe.

The specimens, unearthed in Italy and the UK, have just been confirmed as the earliest known remains of Homo sapiens in Europe.

Careful dating suggests they are more than 41,000 years old, and perhaps as much as 45,000 years old in the case of the Italian "baby teeth".

...

The re-assessments have further importance because palaeoanthropologists can now put modern humans in the caves at the same time as the stone and bone tool technologies discovered there.

There has been some doubt over who created the so-called Aurignacian artefacts at Kents Cavern and the slightly older Uluzzian technologies at Grotta del Cavallo. It could have been Neanderthals, but there is now an obvious association in time with Homo sapiens.

They had in fact discovered the oldest known skeletal remains of anatomically modern humans in the whole of Europe, two international research teams reported Wednesday.

The scientists who made the discovery and others who study human origins say they expect the findings to reignite debate over the relative capabilities of the immigrant modern humans and the indigenous Neanderthals, their closest hominid relatives; the extent of their interactions; and perhaps the reasons behind the Neanderthal extinction. The findings have already prompted speculation that the Homo sapiens migrations into Europe may have come in at least two separate waves, rather than just one.

I'll add the abstracts later. This certainly seems to be incompatible with substantial Neandertal interbreeding. If humans and Neandertals were genetically compatible species, then why would they maintain very separate morphological populations for ~10ka? We would expect the two populations to quickly merge into one. Moreover, a longer period of interbreeding in West Eurasia would have left an excess of "Neandertal" ancestry in modern West Eurasians, something we simply don't observe.

"What the new dates mean", Benazzi summarised, "is that these two teeth from Grotta del Cavallo represent the oldest European modern human fossils currently known. This find confirms that the arrival of our species on the continent – and thus the period of coexistence with Neanderthals – was several thousand years longer than previously thought. Based on this fossil evidence, we have confirmed that modern humans and not Neanderthals are the makers of the Uluzzian culture. This has important implications to our understanding of the development of 'fully modern' human behaviour. Whether the colonisation of the continent occurred in one or more waves of expansion and which routes were followed is still to be established."

Nature (2011) doi:10.1038/nature10484

The earliest evidence for anatomically modern humans in northwestern Europe

Tom Higham et al.

The earliest anatomically modern humans in Europe are thought to have appeared around 43,000-42,000 calendar years before present (43-42 kyr cal BP), by association with Aurignacian sites and lithic assemblages assumed to have been made by modern humans rather than by Neanderthals. However, the actual physical evidence for modern humans is extremely rare, and direct dates reach no farther back than about 41-39 kyr cal BP, leaving a gap. Here we show, using stratigraphic, chronological and archaeological data, that a fragment of human maxilla from the Kent’s Cavern site, UK, dates to the earlier period. The maxilla (KC4), which was excavated in 1927, was initially diagnosed as Upper Palaeolithic modern human1. In 1989, it was directly radiocarbon dated by accelerator mass spectrometry to 36.4-34.7 kyr cal BP2. Using a Bayesian analysis of new ultrafiltered bone collagen dates in an ordered stratigraphic sequence at the site, we show that this date is a considerable underestimate. Instead, KC4 dates to 44.2-41.5 kyr cal BP. This makes it older than any other equivalently dated modern human specimen and directly contemporary with the latest European Neanderthals, thus making its taxonomic attribution crucial. We also show that in 13 dental traits KC4 possesses modern human rather than Neanderthal characteristics; three other traits show Neanderthal affinities and a further seven are ambiguous. KC4 therefore represents the oldest known anatomically modern human fossil in northwestern Europe, fills a key gap between the earliest dated Aurignacian remains and the earliest human skeletal remains, and demonstrates the wide and rapid dispersal of early modern humans across Europe more than 40 kyr ago.

Early dispersal of modern humans in Europe and implications for Neanderthal behaviour

Stefano Benazzi et al.

The appearance of anatomically modern humans in Europe and the nature of the transition from the Middle to Upper Palaeolithic are matters of intense debate. Most researchers accept that before the arrival of anatomically modern humans, Neanderthals had adopted several transitional technocomplexes. Two of these, the Uluzzian of southern Europe and the Châtelperronian of western Europe, are key to current interpretations regarding the timing of arrival of anatomically modern humans in the region and their potential interaction with Neanderthal populations. They are also central to current debates regarding the cognitive abilities of Neanderthals and the reasons behind their extinction1, 2, 3, 4, 5, 6. However, the actual fossil evidence associated with these assemblages is scant and fragmentary7, 8, 9, 10, and recent work has questioned the attribution of the Châtelperronian to Neanderthals on the basis of taphonomic mixing and lithic analysis11, 12. Here we reanalyse the deciduous molars from the Grotta del Cavallo (southern Italy), associated with the Uluzzian and originally classified as Neanderthal13, 14. Using two independent morphometric methods based on microtomographic data, we show that the Cavallo specimens can be attributed to anatomically modern humans. The secure context of the teeth provides crucial evidence that the makers of the Uluzzian technocomplex were therefore not Neanderthals. In addition, new chronometric data for the Uluzzian layers of Grotta del Cavallo obtained from associated shell beads and included within a Bayesian age model show that the teeth must date to ~45,000-43,000 calendar years before present. The Cavallo human remains are therefore the oldest known European anatomically modern humans, confirming a rapid dispersal of modern humans across the continent before the Aurignacian and the disappearance of Neanderthals.

11 comments:

What is more likely, that Châtelperronian and Uluzzian, with their modern technologies, are associated with modern people (who are known to have resided in Eastern Europe at the time), or that Neanderthal magically made a 200,000 year mental leap in 2,000 years?

I liked the Italian analysis of the Uluzzian a couple of years back - that made it pretty convincing to me, even without fossil finds. But, since there are always doubters, this should at least start to settle it.

Perhaps there was a modest amount of interbreeding that simply got diluted over time. But I also think that by 40,000 ya the cultural - and perhaps even mental - barrier was larger than, say, 125,000 ya.

If I remember well the remains of Grotta del Cavallo were first attributed to modern humans, and only after giving the tools to the Uluzian culture it was decided to give them to Neanderthals.If what is written in the document will be confirmed many things need to be rewritten.

The stronger the evidence is that Neanderthals were not that bright, the more likely it is that Neanderthal hybrids would have been selected against in later generations (possibly even many generations later after the hybridization event), which implies that Neanderthal admixture in modern populations may underestimate, rather than overestimate, the amount of admixture that actually took place.

If modern humans outnumbered Neanderthals 9-1 locally, as one recent paper suggested, and hybrids were selected against, the assimilation to oblivion followed by dilution by selection and later waves of low admixture modern humans makes sense.

The absence of Neanderthal Y-DNA or mtDNA, moreover supports the notion that these hybrids really were interspecies hybrids rather than merely different populations of the same species, since it is hard to get that result without applying Haldane's law which applies only in interspecies pairs.

It is quite assumable that every thing is going to turn older isn't it?Take a look at this paper which made the hominins presence in the south asia double older to 1500,000 ybp.http://www.sciencemag.org/content/331/6024/1596.abstractThe quite interesting fact is that they used a new and accurate method which according to them is more correct than others.

The stronger the evidence is that Neanderthals were not that bright, the more likely it is that Neanderthal hybrids would have been selected against in later generations

On the flip side, I would not underestimate that, quite reasonably, there were also significant benefits. Neanderthals had bigger brains, and perhaps significantly different pathways of being smart or wise. They also may have been better at being strong without exercise (like my wife alludes to, describing me), or at a multitude of other things 500,000 years give or take and simple chance at divergence can provide you with.

So, in addition to immune system snatches and related things, it seems to me that both Denisovans and Neanderthals would have been able to offer early, likely less than perfect, AMHs a mighty chance to become much better than originally thought.

Neanderthal cold adaptations would make sense as having selective advantage.

But, the fact that most Neanderthal DNA is in low frequency variants, while very little is in high frequency variants shared in both West and East Eurasian populations, suggests that only a quite small share of the Neanderthal genetic inheritance was selectively advantageous. And, it looks reasonable to infer that Neanderthal admixture may have been in the Near East at the fringe of the Neanderthal range where their adaptations to European climes weren't as beneficial.

"in 13 dental traits KC4 possesses modern human rather than Neanderthal characteristics; three other traits show Neanderthal affinities and a further seven are ambiguous".

Doesn't that suggest a hybrid between the two 'species'? That would also explain the 'transitional technocomplexes'.

"Perhaps there was a modest amount of interbreeding that simply got diluted over time".

Taking the Kent’s Cavern data at face value, and not considering the certainty of recessive traits, we could say that child had 3/23 Neanderthal admixture, or possibly more if the 7 seven ambiguous traits are a product of co-dominant genes.

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